Air blower for fuel cell vehicle

ABSTRACT

Disclosed herein is an air blower for a fuel cell vehicle using bearings. The air blower may include a volute casing, an impeller configured to include a hub and a plurality of wings formed on the outer circumferential surface of the hub and to compress air within the volute casing, a motor casing connected to the volute casing, and a motor configured to include a stator, a rotary shaft lengthily formed to penetrate the stator and configured to have a first side connected to the impeller, a rotator formed on the outer circumferential surface of the rotary shaft, a first bearing provided on the first side of the rotary shaft connected to the impeller, and a second bearing provided on a second side of the rotary shaft.

RELATED APPLICATIONS

This application claims priority to Korean Patent Application No. 10-2013-0042938, filed Apr. 18, 2013 and priority to Korean Patent Application No. 10-2014-0019066, filed Feb. 19, 2014, the contents of both of which are incorporated herein by reference in their entirety.

TECHNICAL FIELD

The present invention relates to an air blower for a fuel cell vehicle using bearings and, more particularly, to an air blower for a fuel cell vehicle, which is capable of supplying air having a low flow rate and high pressure, increasing durability, and reducing noise.

BACKGROUND

Recently, there is an urgent need for the development of a fuel cell vehicle due to problems, such as a continuous rise of oil prices attributable to the exhaustion of fossil energy and environmental pollution attributable to vehicle exhaust gas. A fuel cell is a cell for generating electric power in a reaction process of hydrogen and oxygen, and a fuel cell vehicle includes a fuel cell stack, a hydrogen supply device for supplying hydrogen to the fuel cell stack, and an air blower for compressing air and supplying the compressed air to the fuel cell stack.

An air blower may have various types depending on a pressure and flow rate of air that are necessary for a fuel cell stack.

From among the various types, a volumetric air blower is suitable for a case that requires low specific speed, and a centrifugal air blower is advantageous in that it has smaller friction loss and noise than the volumetric air blower.

The centrifugal air blower includes a volute casing, an impeller disposed within the volute casing and configured to compress air, a motor casing connected to the volute casing, and a motor configured to include a stator, a rotary shaft lengthily formed to penetrate the stator and configured to have an impeller formed on one side of the rotary shaft, and a rotator formed on an outer circumferential surface of the rotary shaft.

Here, air sucked through the impeller is compressed while being accelerated and discharged to the outside. The discharged compression air is supplied to a fuel cell stack.

In particular, an air blower for a fuel cell vehicle requires a low flow rate and high pressure and also requires high durability, low noise, and a wide driving range.

If the centrifugal air blower is designed to have low specific speed, however, there are problems in that it is difficult to secure a surge margin, the Revolutions Per Minute (RPM) may be limited by the durability problem of ball bearings in a motor to which the ball bearings have been applied, and it is difficult to obtain sufficient performance.

Accordingly, there is a need for an air blower for a fuel cell vehicle, which can satisfy durability while satisfying low noise and operational stability, satisfy a low flow rate and high pressure, and secure a surge margin.

BRIEF SUMMARY

Accordingly, the present invention has been made in view of the above problems, and it is an object of the present invention to provide an air blower for a fuel cell vehicle, which is a centrifugal type air blower for a fuel cell vehicle having low specific speed of 28 to 41 and is capable of reducing friction loss and noise and also securing sufficient performance.

It is another object of the present invention to provide an air blower for a fuel cell vehicle, which is capable of supplying air having a low flow rate and high pressure, securing a surge margin, increasing durability, and reducing noise.

In one embodiment, an air blower 1000 for a fuel cell vehicle according to the present invention includes a volute casing 100; an impeller 200 configured to include a hub 210 and a plurality of wings 220 formed on the outer circumferential surface of the hub 210 and to compress air within the volute casing 100; a motor casing 300 connected to the volute casing 100; and a motor 400 configured to include a stator 410, a rotary shaft 420 lengthily formed to penetrate the stator 410 and configured to have a first side connected to the impeller 200, a rotator 430 formed on the outer circumferential surface of the rotary shaft 420, a first bearing 440 provided on the first side of the rotary shaft 420 connected to the impeller 200, and a second bearing 450 provided on a second side of the rotary shaft 420, wherein the air blower 1000 for a fuel cell vehicle has specific speed of 28 to 41.

Furthermore, in one aspect, the impeller 200 has a rotation angle D1 of 60 to 90°.

Furthermore, in an aspect, the impeller 200 has an exit angle D2 of 30 to 50°

Furthermore, in one aspect, a ratio of an exit width L2 with respect to an exit radius L1 in the impeller 200 is 0.04 to 0.09.

Furthermore, in an aspect, the wings 220 of the impeller 200 include a plurality of first wings 221 formed on the outer circumferential surface of the hub 210 and a plurality of second wings 222 configured to have a shorter length than the first wings 221 in a length direction of the hub 210, and the number of second wings 222 is a prime fraction.

Furthermore, in one aspect, the impeller 200 is made of aluminum.

The air blower may further include an air inlet 110 configured to suck air in an axial direction of the blower; an air channel 130 configured to have air, passing through the impeller 200 of the volute casing 100, move therethrough; and an air outlet 120 configured to discharge air in the tangent direction of the volute casing 100.

Furthermore, the air channel 130 of the volute casing 100 may be hollowed in such a way to surround a central region of the volute casing 100 in a circumferential direction of the volute casing 100, and a hollowed cross section of the air channel 130 is proportionately increased in the air flow direction.

Furthermore, in one aspect, the discharge region of the air channel 130 and the air outlet 120 in the volute casing 100 have the same cross section.

Here, the air inlet 110 may be formed by hollowing the central region of the volute casing 100.

The air blower may further include an inflow casing 110 c mounted on a side opposite a side on which the volute casing 100 of the motor casing 300 is provided and configured to have the air inlet 110 formed therein. The air sucked through the air inlet 110 of the inflow casing 110 c is discharged through the air channel 130 and the air outlet 120 via the motor casing 300.

The air blower for a fuel cell vehicle according to the present invention is a centrifugal type air blower for a fuel cell vehicle having low specific speed of 28 to 41 and is advantageous in that it can reduce friction loss and noise and also secure sufficient performance.

Furthermore, the air blower for a fuel cell vehicle according to the present invention is advantageous in that it can supply air having a low flow rate and high pressure, secure a surge margin, increase durability, and reduce noise.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate one or more embodiments of the invention and, together with the description, help to explain the invention. In the drawings:

FIG. 1 is a perspective view of an air blower for a fuel cell vehicle according to the present invention.

FIG. 2 is an exploded perspective view of the air blower for a fuel cell vehicle shown in FIG. 1.

FIGS. 3 and 4 are cross-sectional views of the air blower for a fuel cell vehicle, which are taken along lines AA′ and BB′ in FIG. 1.

FIG. 5 is another cross-sectional view of the air blower for a fuel cell vehicle according to the present invention.

FIGS. 6 to 8 are a perspective view, a partial perspective view, and a lateral plan view of the impeller of the air blower for a fuel cell vehicle according to the present invention.

FIG. 9 is a graph showing a relation between aerodynamic efficiency and specific speed in the air blower for a fuel cell vehicle according to the present invention.

FIG. 10 is a graph showing a relation between exit pressure and aerodynamic efficiency according to rotation angles in the air blower for a fuel cell vehicle according to the present invention.

FIG. 11 is a graph showing a relation between exit pressure and aerodynamic efficiency according to exit angles in the air blower for a fuel cell vehicle according to the present invention.

FIG. 12 is a graph showing a relation between exit pressure and a surge margin according to exit angles in the air blower for a fuel cell vehicle according to the present invention.

FIG. 13 is a graph showing a relation between exit pressure and aerodynamic efficiency according to an exit width to an exit radius in the air blower for a fuel cell vehicle according to the present invention.

FIG. 14 is a graph showing a relation between exit pressure and a surge margin according to an exit width to an exit radius in the air blower for a fuel cell vehicle according to the present invention.

Description of reference numerals of principal elements in the drawings 1000: air blower 100: volute casing 110: air inlet 110c: inflow casing 120: air outlet 130: air channel A1~A8: internal diameter of hollow part A120: internal diameter of air outlet 200: impeller 210: hub 220: wing 221: first wing 222: second wing D1: rotation angle D2: exit angle L1: exit radius L2: exit width 300: motor casing 400: motor 410: stator 420: rotary shaft 430: rotator 440: first bearing 450: second bearing

DETAILED DESCRIPTION

Hereinafter, an air blower 1000 for a fuel cell vehicle according to the present invention is described in detail with reference to the accompanying drawings.

FIG. 1 is a perspective view of an air blower for a fuel cell vehicle according to the present invention, FIG. 2 is an exploded perspective view of the air blower for a fuel cell vehicle shown in FIG. 1, FIGS. 3 and 4 are cross-sectional views of the air blower for a fuel cell vehicle, which are taken along lines AA′ and BB′ in FIG. 1, FIG. 5 is another cross-sectional view of the air blower for a fuel cell vehicle according to the present invention, and FIGS. 6 to 8 are a perspective view, a partial perspective view, and a lateral plan view of the impeller of the air blower for a fuel cell vehicle according to the present invention.

The air blower 1000 for a fuel cell vehicle according to the present invention is configured to include a volute casing 100, an impeller 200, a motor casing 300, and a motor 400.

The volute casing 100 is a part on which the impeller 200 is mounted. The volute casing 100 compresses air by means of the rotation of the impeller 200 and discharges the compressed air.

The volute casing 100 includes an air channel 130 configured to surround the central region of the volute casing 100 in a circumferential direction thereof and to have air passing through the impeller 200 flow therethrough and an air outlet 120 configured to communicate with the air channel 130 and to discharge air in a direction tangent to the volute casing 100.

In the air blower 1000 for a fuel cell vehicle according to the present invention, as shown in FIG. 1, an air inlet 110 into which air flows is formed in the axial direction of the air blower 1000, but the air inlet 110 may be formed by hollowing the central region of the volute casing 100.

That is, in the air blower 1000 for a fuel cell vehicle according to the present invention shown in FIGS. 1 to 4, the air inlet 110, the air channel 130, and the air outlet 120 are formed in the volute casing 100. Air sucked through the air inlet 110 passes through the impeller 200, and the air is discharged to the outside through the air channel 130 and the air outlet 120.

In another embodiment, the air blower 1000 for a fuel cell vehicle according to the present invention may further include an inflow casing 110 c in which the air inlet 110 is formed, as shown in FIG. 5.

In FIG. 5, the air blower 1000 for a fuel cell vehicle according to the present invention includes the inflow casing 110 c mounted on the side opposite the side on which the volute casing 100 of the motor casing 300 is provided. Air sucked through the air inlet 110 of the inflow casing 110 c passes through the impeller 200 via the motor casing 300, and the sucked air is discharged to the outside through the air channel 130 and the air outlet 120.

As described above, the air blower 1000 for a fuel cell vehicle according to the present invention includes both the type in which the air inlet 110 is formed in the volute casing 100 (refer to FIGS. 1 to 4) and the type in which the inflow casing 110 c having the air inlet 110 formed therein is provided in the motor casing 300 on the side opposite the side on which the volute casing 100 is formed (refer to FIG. 5).

Furthermore, the air channel 130 is a region hollowed so that air flows through the air channel 130. The air channel 130 has a sufficient surge margin and a wide driving region, but does not include an additional vane so that it is suitable for a fuel cell vehicle.

The surge margin is an index indicative of stability for a danger of the occurrence of surge. The surge margin is a value obtained by dividing a value of a flow rate at an operation point of the impeller 200, subtracted from a flow rate at a surge point of the impeller 200, by the flow rate at the operation point.

In the air blower 1000 for a fuel cell vehicle according to the present invention, the hollowed cross section of the air channel 130 of the volute casing 100 is proportionately increased in the air flow direction (refer to FIG. 4).

In FIG. 4, angles are indicated at equal intervals of 45° (e.g., 90°, 135°, 180°, 225°, 270°, 315°, and 0° (360°)) around the center of the volute casing 100. The internal diameters of the air channel 130 are indicated by A1 to A7 at the respective angles.

In other words, the air blower 1000 for a fuel cell vehicle according to the present invention has a shape in which the hollowed cross section of the air channel is gradually increased in the air flow direction. The internal diameters A1 to A7 of the air channel 130 are increased in the air flow direction (counterclockwise in FIG. 4), and thus the cross sections thereof are also gradually increased.

Furthermore, the cross section of the discharge region of the air channel 130 is formed to be the same as the cross section of the air outlet 120 so that air compressed by the impeller 200 is transmitted without loss.

That is, the internal diameter A7 of the discharge region of the air channel 130 is formed to be the same as the internal diameter A120 of the air outlet 120.

Accordingly, the air blower 1000 for a fuel cell vehicle according to the present invention is advantageous in that air compressed by the impeller 200 can be supplied to the fuel cell without loss.

The impeller 200 is disposed within the volute casing 100 and is configured to suck air through the air inlet 110 and compress the sucked air. The compressed air passing through the impeller 200 is discharged through the air channel 130 and the air outlet 120.

The impeller 200 of the air blower 1000 for a fuel cell vehicle according to an embodiment of the present invention is shown in FIGS. 6 to 8.

The impeller 200 may be made of aluminum for easy manufacturing.

The impeller 200 includes a hub 210 and a plurality of wings 220 provided on the outer circumferential surface of the hub 210 (refer to FIGS. 6 to 8).

When seeing the impeller 200 at the front in relation to the wings 220, an angle formed by the start point and end point of one wing 220 around the center of the impeller 200 is defined as a rotation angle D1.

Furthermore, an exit angle D2 of the impeller 200 is defined as an angle formed by an exit (i.e., end part) angle of the wing 220 and a tangent line in the circumferential direction of the impeller 200.

Furthermore, an exit radius L1 of the impeller 200 means the radius L1 of the end part of the wing 220 on a meridian plane.

Furthermore, an exit width L2 of the impeller 200 means a length between the inside surface and outside surface of the wing 220 in the axial direction of the impeller 200 at the exit (i.e., end part) of the impeller 200.

The motor casing 300 is connected to the volute casing 100 and configured to include the motor 400 therein.

The motor 400 includes a stator 410, a rotary shaft 420, a rotator 430, a first bearing 440, and a second bearing 450.

The stator 410 is configured to have the center thereof hollowed in the axial direction of the motor 400.

The rotary shaft 420 is configured to penetrate the stator 410 and to have the hub 210 of the impeller 200 connected to one side thereof (i.e., the right side in FIGS. 3 and 5).

The rotator 430 is integrally formed with the outer circumferential surface of the center of the rotary shaft 420.

The first bearing 440 is provided on one side to which the impeller 200 of the rotary shaft 420 is connected and configured to support the rotation of the rotary shaft 420 that is attributable to the rotation of the rotator 430.

The second bearing 450 is configured to support the rotary shaft 420 along with the first bearing 440 and provided on the other side of the rotary shaft 420.

The air blower 1000 for a fuel cell vehicle according to the present invention has the above-described centrifugal construction and may have specific speed of 28 to 41.

The specific speed can be defined by Equation 1 below.

$\begin{matrix} {N_{s} = \frac{N\sqrt{Q}}{\left\{ {\frac{{kRT}_{0}}{k - 1}\left( {{PR}^{\{{k - {1/k}}\}} - 1} \right)} \right\}^{3\text{/}4}}} & \left\lbrack {{Equation}\mspace{14mu} 1} \right\rbrack \end{matrix}$

In Equation 1, N=RPM, Q=volumetric flow rate m³/min, k=a specific heat ratio, R=a gas constant/MW, PR=a pressure ratio, and To=temperature K.

The specific speed is the RPM of the blower that is necessary to discharge a nutrient solution of a unit head (1 m) in a unit flow rate (1 m³/min). Assuming that the amount of discharge Q (m³/min) in the design RPM of the blower N and a total head is H(m), specific speed Ns of the blower is represented by Equation 2 below.

$\begin{matrix} {N_{s} = \frac{N\sqrt{Q}}{H^{3\text{/}4}}} & \left\lbrack {{Equation}\mspace{14mu} 2} \right\rbrack \end{matrix}$

In the air blower 1000 for a fuel cell vehicle according to the present invention, if specific speed is less than 28, aerodynamic efficiency is less than 75% (refer to FIG. 9). In such a case, it is difficult to expect sufficient performance and the fabrication of the impeller 200 is limited because the exit width L2 is inevitable 2 mm or less.

Furthermore, if specific speed exceeds 41, there is a problem in that durability of the first bearing 440 and the second bearing 450 themselves and durability of the entire air blower 1000 for a fuel cell vehicle are deteriorated because the RPM of the first bearing 440 and the second bearing 450 is increased.

Furthermore, FIG. 10 is a graph showing a relation between exit pressure and aerodynamic efficiency according to the rotation angles D1 in the air blower 1000 for a fuel cell vehicle according to the present invention. The air blower 1000 for a fuel cell vehicle according to the present invention may have the rotation angle D1 of 60 to 90°.

As shown in FIG. 10, the impeller 200 of the air blower 1000 for a fuel cell vehicle according to the present invention is formed to have the rotation angle D1 of 60 to 90° in order to secure sufficient exit pressure and also improve aerodynamic efficiency.

Furthermore, FIG. 11 is a graph showing a relation between exit pressure and aerodynamic efficiency according to the exit angle D2 in the air blower 1000 for a fuel cell vehicle according to the present invention, and FIG. 12 is a graph showing a relation between exit pressure and a surge margin according to the exit angle D2 in the air blower 1000 for a fuel cell vehicle according to the present invention. The exit angle D2 of the air blower 1000 for a fuel cell vehicle according to the present invention may be 30 to 50°.

As shown in FIGS. 11 and 12, the exit pressure is reduced according to an increase of the exit angle D2 in a region in which the exit angle D2 is 10° or more. In order to avoid such a problem, the air blower 1000 for a fuel cell vehicle according to the present invention is configured to have an exit angle D2 of 50° or less in order to satisfy sufficient exit pressure and to have an exit angle D2 of 30° or more in order to improve aerodynamic efficiency and a surge margin.

FIG. 13 is a graph showing a relation between exit pressure and aerodynamic efficiency according to the exit width L2 to the exit radius L1 in the air blower 1000 for a fuel cell vehicle according to the present invention, and FIG. 14 is a graph showing a relation between exit pressure and a surge margin according to the exit width L2 to the exit radius L1 in the air blower 1000 for a fuel cell vehicle according to the present invention. In the air blower 1000 for a fuel cell vehicle according to the present invention, a ratio of an exit width L2 with respect to an exit radius L1 in the impeller 200 may be 0.04 to 0.09.

As shown in FIGS. 13 and 14, the air blower 1000 for a fuel cell vehicle according to the present invention, a ratio of the exit width L2 with respect to an exit radius L1 is 0.09 or less in order to satisfy sufficient exit pressure, and a ratio of an exit width L2 with respect to an exit radius L1 is 0.04 or more in order to satisfy aerodynamic efficiency and a surge margin.

Furthermore, in the air blower 1000 for a fuel cell vehicle according to the present invention, the wings 220 of the impeller 200 may include a plurality of first wings 221 formed on the outer circumferential surface of the hub 210 and a plurality of second wings 222 configured to have a shorter length than the first wing 221 in the length direction of the hub 210.

The number of second wings 222 may be a prime fraction.

In the present invention, the term ‘prime fraction’ is a positive integer greater than 1 that is divisible by 1 and itself and may be, for example, 2, 3, 5, 7, 11, 13, and so on.

Each structure has eighfrequency. The air blower 1000 for a fuel cell vehicle according to the present invention is advantageous in that it can minimize the occurrence of noise and a reduction of durability attributable to resonance because it includes the second wings 222 whose number is a prime fraction in order to minimize a possibility that resonance is generated due to overlapping between the frequencies of other structures.

Furthermore, in the air blower 1000 for a fuel cell vehicle according to the present invention, although the wings 220 include the first wings 221 and the second wings 222, each of the first wing 221 and the second wing 222 may have a rotation angle D1 of 60 to 90° and an exit angle D2 of 30 to 50°.

Accordingly, the air blower 1000 for a fuel cell vehicle according to the present invention is a centrifugal type air blower using the first bearing 440 and the second bearing 450 having low specific speed of 28 to 41 and is advantageous in that it can reduce friction loss and noise, supply air having a low flow rate and high pressure, secure a surge margin, and improve aerodynamic efficiency.

The present invention is not limited to the aforementioned embodiments. The present invention may be applied in various ways and may be modified in various forms without departing from the scope of the present invention. 

We claim:
 1. An air blower for a fuel cell vehicle, comprising: a volute casing; an impeller configured to comprise a hub and a plurality of wings formed on an outer circumferential surface of the hub and to compress air within the volute casing; a motor casing connected to the volute casing; and a motor configured to comprise a stator, a rotary shaft lengthily formed to penetrate the stator and configured to have a first side connected to the impeller, a rotator formed on an outer circumferential surface of the rotary shaft, a first bearing provided on the first side of the rotary shaft connected to the impeller, and a second bearing provided on a second side of the rotary shaft, wherein the air blower for a fuel cell vehicle has specific speed of 28 to
 41. 2. The air blower of claim 1, wherein the impeller has a rotation angle of 60 to 90°.
 3. The air blower of claim 1, wherein the impeller has an exit angle of 30 to 50°.
 4. The air blower of claim 1, wherein a ratio of an exit width with respect to an exit radius in the impeller is 0.04 to 0.09.
 5. The air blower of claim 1, wherein: the wings of the impeller comprise a plurality of first wings formed on the outer circumferential surface of the hub and a plurality of second wings configured to have a shorter length than the first wings in a length direction of the hub, and a number of second wings is a prime fraction.
 6. The air blower of claim 5, wherein the impeller is made of aluminum.
 7. The air blower of claim 1, further comprising: an air inlet configured to suck air in an axial direction of the blower; an air channel configured to have air, passing through the impeller of the volute casing, move therethrough; and an air outlet configured to discharge air in a tangent direction of the volute casing.
 8. The air blower of claim 7, wherein: the air channel of the volute casing is hollowed in such a way to surround a central region of the volute casing in a circumferential direction of the volute casing, and a hollowed cross section of the air channel is proportionately increased in an air flow direction.
 9. The air blower of claim 8, wherein a discharge region of the air channel and the air outlet in the volute casing have an identical cross section.
 10. The air blower of claim 7, wherein the air inlet is formed by hollowing a central region of the volute casing.
 11. The air blower of claim 7, further comprising an inflow casing mounted on a side opposite a side on which the volute casing of the motor casing is provided and configured to have the air inlet formed therein, and the air sucked through the air inlet of the inflow casing is discharged through the air channel and the air outlet via the motor casing. 